The rear wiper is mostly an analog mechanical device. There is one automated function, when the front wipers are "on" and the car is in reverse. Otherwise, you control it from the right stalk's end-switch, or the rear-washer cycle (flip right stalk back).
How did you determine that the "motor test ok"?
There are limit switches inside the motor (which reverses the motor for the backstroke, and shuts off in the park position). I'm wondering if these limit switches are the problem. If you're getting switched 12V at the motor leads ("on" when appropriate) but no motion, then that's likely it, and a new motor assy. should fix it.
As far as VIDA, there's no feedback from the wiper motor, so no DTCs. The wipers are an open-loop effector.